Grinding machines and a process for such a grinding, particularly of gearwheel parts for transmissions or flange parts, are already known, in which, in these known grinding machines and processes, several operations or partial operations are, indeed, carried out on a grinding machine; but a complete machining of such types of workpieces on one and the same grinding machine, on the other hand, is not known.
Lathes and grinding machines, by means of which an external cylindrical and an end surface machining of workpieces is carried out, are known from DE 10 2012 012 331 A1.
Two tool stocks positioned opposite to one another, which support several different tools and the external machining on the workpiece, have been described in connection with the known lathes. The workpiece is held by a first workpiece spindle, in which position the external machining and the end point of the workpiece positioned opposite to the clamping point can be machined. From the first workpiece spindle, it is possible to proceed to a workpiece, a second workpiece spindle positioned opposite to this, a so-called counter-spindle, so that the second, end surface of the workpiece that is first of all clamped can also be machined. If the clamping in the counter-spindle does not allow a machining in the area of the end surface, then the workpiece to be machined can be held centrally by means of a tip, which is attached to one of the tool holders or tool headstocks. In this case, however, the clamping remains held by the first tool headstock.
In the grinding machine described, a separate tailstock is positioned opposite the workpiece headstock. A grinding headstock with a grinding wheel can carry out the external cylindrical machining and also grind planar sides on flanges of the workpiece with its front surfaces, if necessary, but not at the immediate end, which is held by the tailstock. A second tool stock is positioned opposite to the grinding headstock and is configured as a multi-function unit. This multi-function unit supports a steady rest and measuring sensors, for example, in order to carry out in-process measurements. In addition, the multi-function unit supports a truing unit, so that the grinding wheel, which is located on the grinding headstock positioned opposite, can be trued. The tailstock and the grinding headstock are thus configured as separate units. The tailstock center attached serves only as a centering for the event that a so-called hub has first been brought into the workpiece. An internal grinding device is not described, either for the lathe or for the grinding machine.
A process and a grinding tool for the internal cylindrical and surface grinding of a workpiece in the form of a gearwheel are described in DE 10 2005 018 959 B3. An internal cylindrical grinding of the bore and a subsequent surface grinding of at least one planar surface on one side of the gearwheel are thus carried out with one and the same grinding wheel, which is profiled in such a way that two different conical areas are provided for the respective grinding tasks. A front conical area grinds the inner bore of the gearwheel, whereas a collar-like grinding area stepped behind the conical area is inserted for the one external planar surface on the gearwheel. The grinding spindle is thereby placed so obliquely, with reference to the cone angle, that the surfaces of the inner bore are ground coaxial to the central axis of the gearwheel. Corresponding to the cone angle of the second grinding area for the planar surfaces, such an angle of attack for the profiled grinding wheel is selected that the planar surface can be ground perpendicular to the central axis of the gearwheel. By means of such a profiled grinding wheel, the internal surface of the bore and the planar surface can only be ground in succession on the one external surface of the gearwheel. Clamping conditions and devices for the grinding of the planar side of the gearwheel positioned opposite are also not described.
A device for the grinding of workpieces with a workpiece holder and with at least one grinding tool is described in DE 197 53 797 C2. The workpiece can also be a gearwheel, in which the machining of its end surfaces is likewise carried out. The workpiece is clamped in a clamping device of the tool holder and the machining processes for the internal diameter, as well as the external contours, i.e., the planar sides, take place in succession there. After the finish grinding of the planar sides located on one side of the gearwheel, as well as of the internal diameter, the workpiece is unloaded from the machine by means of a hand-over device. A grinding of the opposing planar side is also not described in this known machine.
In addition, a grinding machine for the internal cylindrical, planar, and external cylindrical grinding is known from DE 36 28 977 A1. In this known grinding machine, a workpiece headstock is provided with a clamping chuck for the workpiece to be ground as a single clamping device.
The grinding of bores, external cylindrical and planar external surfaces is carried out by means of corresponding grinding wheels, which can be brought into grinding engagement on separate CNC-controlled grinding headstocks. A grinding of planar sides and opposing planar sides on one and the same workpiece is not described. The placement of two independent grinding headstocks has the positive result that both the external contours and an internal grinding of the bore can be processed simultaneously.
The known grinding machines and processes for the production of corresponding workpieces on these grinding machines have in common the fact that the workpiece to be ground in a machine cannot be machined completely.
Because a complete grinding process of the workpieces described above on one and the same grinding machine is not possible in the known grinding machines, additional machines, or at least corresponding additional grinding stations, must be made available for the complete machining of such types of workpieces. It is disadvantageous in this concept that a separate work sequence is therefore necessary, and the workpiece must be brought into another machine tool or an additional station for that purpose. Additional conveying devices are necessary for this. In addition, this results in the disadvantage that the workpieces must be exposed again to other ambient temperatures, and thus changed environmental influences, up to the loading in the second machine or second station, respectively, and thus also expand differently due to different thermal environmental conditions, if applicable, which can have a direct influence on the later precision of production.
In addition, a numerically controlled lathe is described in DE 195 13 963 A1, by means of which workpieces can be machined simultaneously on a workpiece spindle and on a counter-spindle, both internally and externally. The workpiece to be machined is clamped to the so-called workpiece spindle, as well as on the counter-spindle, and each can be provided with a drilling tool with an inner bore, whereby it can also be externally ground at the same time by means of tools, which are positioned on a tool support. Throughout the entire machining, the workpiece remains, in one and the same clamping operation, in the respective clamping chuck, and can thus not be machined in the clamping area.
A machine tool, by means of which cylindrical and planar external surfaces as well as bores can be machined on one tool, is described in DE 603 03 672 T2. For that purpose, a series of tool headstocks and a workpiece headstock are provided, so that the various tasks can be carried out on the workpiece. A complete machining is likewise not possible, because the workpiece remains clamped in the clamping chuck during the numerous machining processes to be carried out in the workpiece headstock.
A cylindrical grinding machine with numerical control for the grinding of chuck and pointed workpieces is described in DE 38 17 161 A1. By means of this known cylindrical grinding machine, internal grinding, external grinding, and planar grinding can be carried out between centers and with center and chuck. In the machining of so-called chuck workpieces, these remain clamped in the clamping chuck during the machining of the workpiece. When grinding so-called pointed workpieces, the external surfaces of the workpiece can, of course, be machined essentially completely, but a machining of bores is excluded in this clamping operation.
In the known grinding concepts, it is also disadvantageous that great difficulties result for the process planning, and a greater effort for the monitoring of the respective machining steps is necessary. This leads to greater costs because, for example, measuring instruments must be provided twice, if applicable.
In summary, it is to be noted that, in the known grinding machines or the processes carried out on the same, the present disadvantages lead to the fact that the workpieces are subject to certain restrictions in connection with highly precise production and are, on the other hand, more expensive to produce and must therefore be produced with higher production costs.